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Chinese scientists develop high-efficiency daytime cooling materials

November 5, 2018

a team of Chinese sponge tensile mechanics has developed a high-performance daytime cooling material, which can effectively radiate heat to the outside and have a good cooling effect. New materials can be directly coated on the surface of objects with any texture like paint, and can also be combined with different pigments to achieve different colors

no matter which component Columbia University tests, it is necessary to empty it with a drill bit in advance. Yang Yuan and Yu Nanfang from the Department of Applied Physics and applied mathematics published a paper in the new issue of science, saying that the new material they developed is a "polyvinylidene fluoride hexafluoropropylene copolymer" with multi-scale micro nano pore structure. The film made of this material has a high reflectivity of 96% to 99.6% in the sunlight band, It has a high emissivity of 97% in the infrared radiation window, and can realize the refrigeration of Chinese coatings without electric energy in the daytime

the test results show that in the dry environment with sufficient light, the surface temperature of the film can be about 5.9 ℃ lower than the ambient temperature; In humid environment, the film temperature can be about 2.9 ℃ lower than the ambient temperature. It is reported that in this porous film, the refractive index of polyvinylidene fluoride is very different from that of air, which can effectively scatter sunlight, including ultraviolet, visible and near-infrared light, so as to achieve high reflectivity and will not be heated by sunlight; The micron porous structure improves the emissivity of the material and increases the outward thermal radiation

it is understood that previously, the preparation of similar functional materials required complex vacuum deposition equipment, and it was difficult to directly cover the surface of objects with any shape and texture. The new material has the advantages of low cost and strong applicability, and can be directly coated on any surface such as plastic, metal and wood

Yang Yuan told Xinhua news agency that the surface of buildings often requires color. This material can be combined with pigments to achieve color and reflect the invisible near-infrared light in the sun. Compared with traditional coatings, it can significantly reduce the temperature of buildings

Chen Gang, Professor of Mechanical Engineering Department of Massachusetts Institute of technology, commented that technically speaking, the coatability of materials can reduce the cost, and the application leads to a wide range of samples accepted by the near-infrared model. (Zhou Zhou)